This stuff is like a damn riddle. I hope Barr chimes in and sheds some light on this whole thing.
Any chance you can find the article/research that suggests a whey/casein blend for great muscle protein synthesis? [/quote]
LaCroix M, et al. Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement. Am J Clin Nutr. 2006 Nov;84(5):1070-9.
PURPOSE: To compare the postprandial utilization of dietary nitrogen from [15N]-labeled micellar caseins (MC), milk soluble protein isolate (MSPI ï¿½?? which is synonymous with whey), and total milk protein (TMP).
METHODS: 23 healthy subjects, 24-31 years old, ingested a meal containing MC, MSPI, or TMP. [15N], a stable isotope of nitrogen, was measured for an 8-hr period in plasma amino acids, proteins, and urea and in urinary
RESULTS: The transfer of dietary nitrogen to urea occurred earlier after MSPI ingestion than after MC and TMP ingestion, and concentrations remained high for 8 h, concomitantly with higher but transient hyperaminoacidemia
and a higher incorporation of dietary nitrogen into plasma amino acids. In contrast, deamination, postprandial hyperaminoacidemia, and the incorporation of dietary nitrogen into plasma amino acids were lower in the MC and TMP groups. Total postprandial deamination values were highest in the MSPI
CONCLUSIONS: Despite its high Protein Digestibility Corrected Amino Acid Score, MSPI causes a rate of amino acid delivery that is too rapid to sustain an anabolism during the postprandial period. TMP topped the field in all of the tests.
SPONSORSHIP: Arilait Research and the French Office of Research and Technology.
As expected, whey caused an immediate spike in post-meal hyperaminoacidemia. However, this was followed by marked hypoaminoacidemia by the sixth hour after the meal, which was
not seen in the other groups. Also, the transfer of dietary nitrogen to urea was significantly higher in the whey group than in the other groups, especially during the first 2 hours. This means that the rapid and substantial rise in blood amino acids caused by whey was accompanied by a high rate of excretion of its nitrogen component. This led the authors to conclude that
wheyï¿½??s higher content of indispensable amino acids (including leucine) was counterbalanced by high rates of amino acid deamination, reducing its potential net anabolic effect compared to the other treatments.
Interestingly (but perhaps not too surprisingly), total milk protein was the superior performer in all parameters, with casein in the middle, and whey in last place. To quote the conclusion, ï¿½??This result, together with the hypoaminoacidemia observed 4 h after the ingestion of MSPI, strongly suggests that a too-rapid dietary AA delivery cannot support the anabolic requirement throughout the postprandial period.ï¿½?? This is yet another
indication that low-tech, inexpensive cow milk may be an ideal food for supporting muscle tissue, especially for those who donï¿½??t
have (or wonï¿½??t bother with) a high meal frequency.
Spirited debate is a fun thing to watch (and participate in). Anssi Manninen, a science journalist and owner of a line of products including whey hydrolysate, wrote a letter in disagreement with the conclusion and entitled his letter, ï¿½??Postprandial nitrogen utilization and misinterpretation of dataï¿½??. The authors felt this accusatory title was false because as stated in their reply, ï¿½??..our conclusion was not a suggestion but a direct demonstration based on tracer kinetic data, and Manninen did not provide any data to suggest any misinterpretation of our data.ï¿½??
Manninen contends that the authorsï¿½?? conclusion is misleading. He attempts to support his stance by citing one study showing whey hydrolysate beating casein for fat loss and lean mass gain over a period of 10 weeks. This would be a stronger argument if there werenï¿½??t at least two other published trials suggesting that a whey/casein blend is superior for lean mass and strength gains. Manninen fails to mention these trials.
Finally, Manninen states that slow proteins are best suited for prolonged periods between eating, and fast proteins are best used post-workout. Instead of supporting this claim by directly referencing primary research, he references his own secondary research review article on post-exercise recovery. Incidentally, his article makes no mention of how substrates ingested pre-exercise influence post-exercise physiological demands. Nor
does he mention the limitations of the current majority of post-exercise research on overnight-fasted subjects.
The bottom line is that the whey vs. casein post-workout ï¿½??battleï¿½?? is not a closed case. There is support on both sides, and currently thereï¿½??s more support for a blend of the two proteins than either in isolation. Wait a minute, thatï¿½??s how they occur in nature ï¿½?? as a blend… And it might be optimal that way, what a concept.